Preparative electrofocusing procedures have been developed for the quantitative purification of proteins from mixed saliva or submandibular saliva. The saliva protein mixtures are first electrofocused using Bio-lyte electrofocusing gel containing ampholine carriers in the pH range 3.5 to 10. Following electrophoresis the gel is divided into 7 fractions with each fraction containing proteins within specific limits of pH. The fractions are transferred to small columns and the component proteins are eluted from the gel. The eluates are subjected to electrofocusing in the same system containing ampholines in narrower pH ranges. The separated protein zones are removed individually and eluted from the electrofocusing gel. At present 12 proteins from mixed saliva and 8 proteins from submandibular saliva have been obtained in purity as judged by analytical isoelectric focusing analysis. The ectocellular (cell surface-associated) proteinase obtained from Strep. mutans, Strep. sanguis, Strep. mitior or Strep. salivarius has been found to be tightly bound to a fraction of the cell wall-cell membrane fraction which is sedimentable by low-speed centrifugation (2,000xg). The enzyme complexes from the different species or oral streptococci are affected by different inhibitor or activator agents.